This specification relates to backup power sources.
Data center facilities are often used by providers to deliver Internet services to users. A data center, such as a server farm, typically contains thousands of server processing devices. Within the data centers the processing devices are arranged in racks, and each rack may contain dozens of servers. Assuming the power required for a single rack may be in the order of 50 kW, and that there may be hundreds of racks in a data center, it is not uncommon for a data center to have a power requirement on the order of megawatts.
Data center facilities range in critical levels according to the cost of down time to a business that utilizes the particular data center, the cost of ownership for the data center, and other factors. Typically, a data center facility includes redundant power systems to provide power to the server in the event of a power anomaly (e.g., blackout from utility provider, unstable utility power, etc.). Data center facilities utilize in-rack batteries and diesel generators to provide back-up power during a power anomaly. In-rack batteries are sized as small as possible to cover short-durations and minimize cost and size of the battery. The diesel generators are designed to provide power for longer-duration power anomalies. The determination of which source provides power during the power anomaly is dependent upon the duration of the power anomaly.